§  90.475   Operation of internal transmitter control systems in specially
equipped systems.

   (a) An internal transmitter control system need not be designed to meet
   the requirements of § 90.473 if it meets the following requirements:

   (1) All operating positions must be located on premises controlled by
   the licensee.

   (2) An internal transmitter control system may be used in conjunction
   with other approved methods of transmitter control and interconnection
   so long as the internal transmitter control system, itself, is neither
   accessed from telephone positions in the public switched telephone
   network (PSTN), nor uses dial-up circuits in the PSTN. Licensees with
   complex communications systems involving fixed systems whose base
   stations are controlled by such systems may automatically access these
   base stations through the microwave or operational fixed systems from
   positions in the PSTN, so long as the base stations and mobile units
   meet the requirements of § 90.483 and if a separate circuit is provided
   for each mode of transmitter operation ( i.e. , conventional, dial-up
   or Internet).

   (3) The system must be designed so that upon completion of a
   transmission, the base station transmitter(s) will close down
   automatically within 3 seconds.

   (4) To guard against malfunctions, the system must also be designed so
   that the base station(s) will be deactivated by an automatic timing
   device when a modulated signal is not transmitted for a period of three
   (3) consecutive minutes.

   (5) The system must include automatic monitoring equipment, installed
   at the base station transmitter site(s), which will prevent the
   activation of the system when signals of other co-channel stations are
   present.

   (b) [Reserved]

   [ 43 FR 54791 , Nov. 22, 1978, as amended at  44 FR 67125 , Nov. 23, 1979;
    47 FR 17521 , Apr. 23, 1982;  72 FR 35199 , June 27, 2007]

Interconnected Systems